DESCRIPTION.
| Material | steel |
| Total length | 3.83 feet |
| Length of bore | 3.43 feet |
| Travel of projectile | 3.10 feet |
| Calibre | 1.65 inches |
| Weight | 121 pounds |
| Grooves | 10 |
| Twist of rifling, uniform | 1 in 29.83 cals. |
| Muzzle-velocity | 1298 ft.-sec. |
| Maximum range | 3500 yards |
The gun (Fig. 2) consists of the body and the breech mechanism.
Fig. 2.
The body of the gun is made from a single forging of oil-tempered and annealed steel. The trunnion-ring is screwed on the gun-body just forward of the reinforce, and provides a support for the front sight. The bore is rifled with a uniform right-hand twist. The lands are very narrow in proportion to the grooves, and are ten in number.
The Breech-block is a solid prismatic block of steel with rounded corners, having a horizontal movement in a mortise cut completely through the breech of the gun. The front face of the block is perpendicular to the axis of the bore, whilst the rear face is slightly inclined. The left end of the block is bored to form a prolongation of the chamber when the breech is open, and its front upper corner is cut away to allow free movement of the extractor.
The horizontal movement of the breech-block is limited by the stop-bolt, which, passing through the breech of the gun, engages in a guide in the upper part of the block.
In the right end of the breech-block is mounted a shaft on which is secured the locking-screw, and which terminates in a handle for manœuvring. The thread of the locking-screw is cut away for about 100°, in such a manner that the breech-block may be locked or unlocked by a half-turn of the handle.
The Extractor is a single piece of steel working in a longitudinal groove in the top of the breech-mortise. Its forward end is formed into a claw to grasp the head of the cartridge. On the same side as the claw is a stud which, following a groove in the top of the breech-block, imparts motion to the extractor.
The Vent is a cylindrical channel passing diagonally through the breech and breech-block, and changing direction in the block so as to follow the axis of the bore.
The friction-primer cannot be inserted until the two parts of the vent are in prolongation from the complete closing and locking of the breech-block. The ordinary friction-primer is used.
NOMENCLATURE.
The Mechanism.—(b) breech-block; loading-hole; (s) stop-bolt; spring washer; (r) stop-bolt guide; (e) extractor; (h) extractor-hook; (a k) extractor-guide; (c) locking-screw; locking-screw shaft; locking-screw pin; (l) handle; stop; stop keep-screw.
Fig. 3.
ACTION OF THE MECHANISM.
The gun having been fired, the handle is turned to the rear, unlocking the block and starting it in the mortise. Drawing the handle smartly to the right, the breech is opened, the extractor, actuated by the movement of the block, commences to move very slowly back with a powerful leverage, starting the cartridge-case from its seat. When the breech-block has moved sufficiently to unmask the bore, the change of direction in the extractor-guide causes the extractor to make a quick movement to the rear, throwing the cartridge clear of the gun.
A new charge being inserted, it is pushed home until the head of the cartridge brings up against the extractor. The breech is now closed by pushing it smartly to the left, and is locked by turning the handle to the front. A primer may now be inserted in the vent, and the gun is ready for firing.
DIRECTIONS FOR DISMOUNTING THE MECHANISM.
Unscrew the stop-bolt about four turns, or remove completely.
Withdraw breech-block.
Remove extractor, which is now free.
In general nothing further need be dismounted for cleaning and inspection.
To dismount completely continue as follows:
Remove locking-screw pin with screw-driver.
Remove stop keep-screw.
Drive out stop with the drift, interposing a bit of wood or leather to avoid bruising the stop.
Withdraw handle and locking-screw shaft.
Remove locking-screw.
To mount, proceed in reverse order.
CARE AND PRESERVATION.
The gun requires no special care beyond that of being kept clean, free from rust and undefaced.
Brick-dust or gritty substances must never be used on any part of the gun.
The parts of the mechanism must never be scraped with knives or metal, or be defaced or roughened in any way.
All parts of the gun must be kept lightly oiled as a protection from rust.
After firing, the gun should invariably be thoroughly cleaned. To do this, dismount the mechanism completely and wash every part thoroughly with warm fresh-water soapsuds; mechanism, breech-block, mortise, and barrel should all be treated alike.
After thoroughly scrubbing all parts, dry them carefully and let all stand for a short time to air and dry off the moisture.
After drying, rub all parts over with a well-oiled rag.
Mount the mechanism.
On the march the breech and muzzle should always be protected by the covers supplied for the purpose.
When parked, guns and carriages should be covered with paulins.
SIGHTS.
The Front Sight is a plain roughened steel point-sight, and is permanently fixed to the right rim-base.
Fig. 4.
The Bar Tangent Sight ([Fig. 4]) is a plain vertical bar-sight carrying a sliding leaf conveniently graduated. Both the bar and the leaf have clamp-screws to fix them in position. The tangent sight is only mounted on the gun when in action, being at other times removed to avoid injuring it.
The bar is graduated to 15°, each being subdivided into six parts. It may be graduated in yards or metres. It is compensated for natural drift. A vernier-mark on the head of the sight and graduations on the sliding leaf correct ordinary deviations.
The Gunner's Quadrant, for mountain-guns, is a small pocket-quadrant with a spirit-level limb pivoted. On the arc are inscribed both the degrees of elevation and ranges corresponding to the gun for which it is used. It is thoroughly reliable both for direct and curved fire, and to a very great extent supplants the sight-bar.
The recoil is checked by rope-brakes, hooked to the trail-handles and passed around the felloes of the wheels. No limber is used, but a pole which is readily attached to the trail is provided for hauling the carriage.
AMMUNITION.
The ammunition is fixed, and consists of common shell and canister.
| Weight of round (common shell) | 2.62 pounds |
| Weight of shell, filled | 1.95 pounds |
| Weight of round (canister) complete | 3.47 pounds |
| Weight of canister | 2.8 pounds |
| Number of balls in canister | 30 |
| Powder-charge | 5½ oz. mortar |
| Bursting-charge of shell | 1.8 oz. |
| Weight of cartridge case empty | 5.3 oz. |
| Weight of fuze | 1.9 oz. |
The drawn metallic cartridge-case ([Fig. 5]) is of brass, and is drawn from the solid metal to shape. It is reinforced at the base by inside (c) and outside (b) cups of the same metal. The head (d) is fastened to the base by brass rivets which clamp the body, cups, and head solidly together. A vent (v) is pierced through the head of the cartridge, and five eccentric flash-holes (a) through the reinforcing-cups. The jet of flame from the primer, entering the vent, lifts the reinforcing-cups and forces its way through the flash-holes to the charge. The charge being ignited, the pressure of the gas immediately forces back the reinforcing-cups and seals the vent. The charge, consisting of 5½ oz. of black powder, is well shaken down and separated from the base of the projectile by a felt wad. When smokeless powder is employed, an igniter containing about 40 grains (3 grammes) of musket-powder is placed in the bottom of the cartridge-case. The vent is sealed with a thin coating of wax.
Fig. 5.
Fig. 6.
Fig. 7.
The Common Shell ([Fig. 6]) is of the cylindro-ogival pattern with a brass band, and is fitted with a base percussion-fuze. It contains a bursting-charge of about 1¾ oz. (950 grammes) of musket-powder.
The Canister ([Fig. 7]) consists of a thin envelope of drawn brass, containing thirty hardened 1-oz. lead balls packed in sulphur. On the body is an annular stop to prevent inserting too far into the cartridge-case. The cartridge-case can be recharged on an average about eight times.